Optical module and associated methods

ABSTRACT

An optical module includes a laser light supply system and a chip disposed within a housing. The chip includes a laser input optical port and a transmit data optical port and a receive data optical port. The optical module includes a link-fiber interface exposed at an exterior surface of the housing. The link-fiber interface includes a transmit data connector and a receive data connector. The optical module includes a polarization-maintaining optical fiber connected between a laser output optical port of the laser light supply system and the laser input optical port of the chip. The optical module includes a first non-polarization-maintaining optical fiber connected between the transmit data optical port of the chip and the transmit data connector of the link-fiber interface. The optical module includes a second non-polarization-maintaining optical fiber connected between the receive data optical port of the chip and the receive data connector of the link-fiber interface.

CLAIM OF PRIORITY

This application claims priority under 35 U.S.C. 119(e) to U.S.Provisional Patent Application No. 62/453,457, filed Feb. 1, 2017, thedisclosure of which is incorporated herein by reference in its entiretyfor all purposes.

BACKGROUND 1. Field of the Invention

The present invention relates to optical data communication.

2. Description of the Related Art

Optical data communication systems operate by modulating laser light toencode digital data patterns. The modulated laser light is transmittedthrough an optical data network from a sending node to a receiving node.The modulated laser light having arrived at the receiving node isde-modulated to obtain the original digital data patterns. Therefore,implementation and operation of optical data communication systems isdependent upon having reliable and efficient mechanisms for transmittinglaser light and detecting laser light at different nodes within theoptical data network. In this regard, it can be necessary to transmitlaser light from a laser to a chip, and transmit modulated light from achip to another chip. It is within this context that the presentinvention arises.

SUMMARY

In an example embodiment, an optical module includes a housing thatincludes a laser light supply system and a chip. The laser light supplysystem includes a laser output optical port. The chip is includes alaser input optical port and a transmit data optical port and a receivedata optical port. The optical module also includes a link-fiberinterface exposed at an exterior surface of the housing. The link-fiberinterface includes a transmit data connector and a receive dataconnector. The optical module also includes a polarization-maintainingoptical fiber optically connected between the laser output optical portand the laser input optical port of the chip. The optical module alsoincludes a first non-polarization-maintaining optical fiber opticallyconnected between the transmit data optical port of the chip and thetransmit data connector of the link-fiber interface. The optical modulealso includes a second non-polarization-maintaining optical fiberoptically connected between the receive data optical port of the chipand the receive data connector of the link-fiber interface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a diagram of an optical module for use in a datacommunication system, in accordance with some embodiments.

FIG. 2 shows a diagram of how a fiber set is used to connect the chip tothe laser light supply system and the link-fiber interface, inaccordance with some embodiments.

FIG. 3 shows a diagram of how four fiber sets are connected to a givenone of the chips, in accordance with some embodiments.

FIG. 4A shows a lens assembly for use in attaching an optical fiber tothe chip in a parallel-coupled configuration, in accordance with someembodiments of the present invention.

FIG. 4B shows an example cleaving of the optical end structure withexample angles, in accordance with some embodiments of the presentinvention.

FIG. 4C shows an interface of eight instances of the lens assembly withthe chip, in accordance with an example embodiment of the presentinvention.

FIG. 4D shows a top-down view of the chip of FIG. 4C, in accordance withsome embodiments of the present invention.

FIG. 4E shows Detail E of FIG. 4D, in accordance with some embodimentsof the present invention.

FIG. 5A shows a vertical cross-section through a connector of the chip,corresponding to View A-A as shown in FIG. 1, in accordance with someembodiments.

FIG. 5B shows a vertical cross-section through a connector of the chip,corresponding to View B-B as shown in FIG. 1, in accordance with someembodiments.

FIG. 5C shows a vertical cross-section through a connector of the chip,corresponding to View C-C as shown in FIG. 1, in accordance with someembodiments.

FIG. 5D shows a vertical cross-section through a connector of the chip,corresponding to View D-D as shown in FIG. 1, in accordance with someembodiments.

FIG. 5E shows a SQUID assembly, in accordance with some embodiments.

FIG. 6 shows a diagram of how the SQUID assembly can be connected to achip, in accordance with some embodiments.

FIG. 7 shows a diagram of how the SQUID assembly can be connected to thelaser light supply system, in accordance with some embodiments.

FIG. 8 shows the diagram of FIG. 7, with four breakout assembliesprovided to connect the four connectors to the output interface of thelaser light supply system, in accordance with some embodiments.

FIG. 9A shows an example vertical cross-section through one type of PMFribbon, in accordance with some embodiments.

FIG. 9B shows an example vertical cross-section through another type ofPMF ribbon, in accordance with some embodiments.

FIG. 9C shows an example vertical cross-section through apolarization-maintaining multicore optical fiber (PMMF), in accordancewith some embodiments.

FIG. 9D shows an example vertical cross-section through another type ofPMF ribbon, in accordance with some embodiments.

FIG. 10 shows an example of a quasi-polarization maintaining opticalfiber assembly (QPMFA), in accordance with some embodiments.

FIG. 11 shows a plot of birefringence (beat length) as a function ofradius of curvature of SMF fiber, in accordance with some embodiments.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth inorder to provide an understanding of the present invention. It will beapparent, however, to one skilled in the art that the present inventionmay be practiced without some or all of these specific details. In otherinstances, well known process operations have not been described indetail in order not to unnecessarily obscure the present invention.

FIG. 1 shows a diagram of an optical module 100 for use in a datacommunication system, in accordance with some embodiments. In someembodiments, the optical module 100 can have an exterior housingsurrounding an interior volume, where the exterior housing is configuredto protect components installed within the interior volume. Also, invarious embodiments the exterior housing of the optical module 100 caninclude vents to enable cooling air flow through the interior volume.And, in some embodiments, the optical module 100 can be equipped withforced air cooling, such as fan, to push or draw air through theinterior volume of the exterior housing. In some embodiments, theexterior housing of the optical module 100 can be configured as a box.However, in various embodiments, the exterior housing of the opticalmodule 100 can have essentially any size and shape that enablesinstallation of required components within the interior volume of theexterior housing.

In some embodiments, the optical module 100 includes a laser lightsupply system 101. The laser light supply system 101 is configured toproduce and transmit N different wavelengths of light (λ₁ to λ_(N))collectively at each of multiple laser outputs within an outputinterface 102. It should be understood that the laser light supplysystem 101 can include multiple lasers, perhaps one laser per wavelengthof light, and can include an arrangement of optical amplifiers, opticalsplitters, and optical combiners as needed to produce and collectivelyoutput the N different wavelengths of light (λ₁ to λ_(N)) at each ofmultiple laser outputs within the output interface 102. An example laserlight supply system 101 is described in co-pending U.S. patentapplication Ser. No. 15/277,968, which is incorporated herein byreference in its entirety. In some embodiments, the laser light supplysystem 101 is installed on a printed circuit board, with the printedcircuit board installed within the optical module 100.

The optical module 100 also includes a number of chips 103A, 103B, 103C,103D, where each chip 103A-103D is an integrated photonic chip. Invarious embodiments, any of the chips 103A-103D can include variousdevices, such as optical, electrical, electro optic, and combinationsthereof. In some embodiments, the chips 103A-103D are transponder chips.In some embodiments, any of the chips 103A-103D can include Si, GaAs,InP, InGaAsP, Ge, GaN, etc. In some embodiments, any of the chips103A-103D can be a CMOS chip. In some embodiments, any of the chips103A-103D can have both CMOS circuits and optical circuits. In theseembodiments, any of the chips 103A-103D can include custom logic, CPUs,GP-GPUs, switch logic, DRAM, NAND, 3D XPoint, or any other logic,analog, or memory element. Also, in some embodiments, the any of thechips 103A-103D can include one or more vertical grating couplers toenable optical connection with one or more external optical fibers. Insome embodiments, the chips 103A-103D are transceiver chips thatfunction to provide an optical communication link over link-fiber withinan optical data communication network. As mentioned above, any chip103A-103D configured as a transceiver chip can also have otherintegrated functions and perform computations, memory storage, andessentially any other function normally associated with a computer chip.

In the example of FIG. 1, the optical module 100 includes four separatechips 103A-103D. However, it should be understood that in variousembodiments, the optical module 100 can include either less than fourchips or more than four chips. It should be understood that increasingthe number of chips within the optical module 100 provides forleveraging of the cost of the laser light supply system 101 over moredata communication interfaces, which reduces the cost of the laser lightsupply system 101 per data communication interface. In some embodiments,the chips 103A-103D are installed on one or more printed circuit boards,with the printed circuit boards installed within the optical module 100.In some embodiments, the laser light supply system 101 is installed on aprinted circuit board that is separate from printed circuit board(s) onwhich the chips 103A-103D are installed.

The optical module 100 also includes a link-fiber interface exposed on asurface of the exterior housing of the optical module 100, such as on afront panel of the optical module 100 by way of example. The link-fiberinterface is configured to provide optical connections between the chips103A-103D and link-fiber within an optical data communication network,where the link-fiber is the medium of communications. The link-fiberinterface includes a number of transmit/receive optical fiberconnectors, such as LC duplex connectors. It should be understood thatin various embodiments, the link-fiber interface can be configured usingessentially any type of optical fiber connector(s). For example, invarious embodiments, the transmit and receive optical fiber connectorscan be LC, FC, SC, or whatever connector type is desired. In the exampleof FIG. 1, the link-fiber interface includes sixteen transmit/receiveoptical fiber connectors, where each transmit optical connector isdesignated T and each receive optical connector is designated R. Itshould be understood that in various embodiments, the number oftransmit/receive optical fiber connectors in the link-fiber interface isdependent upon the number and configuration of chips, e.g., 103A-103D,within the optical module 100. In the example of FIG. 1, each of thechips 103A-103D includes four transmit/receive optical ports. Therefore,the four chips 103A-103D collectively communicate with sixteentransmit/receive optical fiber connectors at the link-fiber interface.

Each transmit optical port on a given chip 103A-103D is associated witha separate laser input port on the given chip. Therefore, in the exampleof FIG. 1, because each chip 103A-103D has four transmit optical ports,and each chip 103A-103D has four laser input optical ports.Specifically, chip 103A has four laser input optical ports opticallyconnected to four laser output ports of the laser light supply system101 by optical fibers L1, L2, L3, L4, respectively. And, the chip 103Ahas four transmit optical ports optically connected to four transmitoptical fiber connectors T at the link-fiber interface by optical fibersT1, T2, T3, T4, respectively. Also, chip 1038 has four laser inputoptical ports optically connected to four laser output ports of thelaser light supply system 101 by optical fibers L5, L6, L7, L8,respectively. And, the chip 1038 has four transmit optical portsoptically connected to four transmit optical fiber connectors T at thelink-fiber interface by optical fibers T5, T6, T7, T8, respectively.Also, chip 103C has four laser input optical ports optically connectedto four laser output ports of the laser light supply system 101 byoptical fibers L9, L10, L11, L12, respectively. And, the chip 103C hasfour transmit optical ports optically connected to four transmit opticalfiber connectors T at the link-fiber interface by optical fibers T9,T10, T11, T12, respectively. Also, chip 103D has four laser inputoptical ports optically connected to four laser output ports of thelaser light supply system 101 by optical fibers L13, L14, L15, L16,respectively. And, the chip 103D has four transmit optical portsoptically connected to four transmit optical fiber connectors T at thelink-fiber interface by optical fibers T13, T14, T15, T16, respectively.

Additionally, in accordance with duplex configuration of the link-fiberinterface in the example of FIG. 1, there is a separate receive opticalfiber connector at the link-fiber interface for each transmit opticalfiber connector at the link-fiber interface. Specifically, the chip 103Ahas four receive optical ports optically connected to four receiveoptical fiber connectors R at the link-fiber interface by optical fibersR1, R2, R3, R4, respectively. And, the chip 1038 has four receiveoptical ports optically connected to four receive optical fiberconnectors R at the link-fiber interface by optical fibers R5, R6, R7,R8, respectively. And, the chip 103C has four receive optical portsoptically connected to four receive optical fiber connectors R at thelink-fiber interface by optical fibers R9, R10, R11, R12, respectively.And, the chip 103D has four receive optical ports optically connected tofour receive optical fiber connectors R at the link-fiber interface byoptical fibers R13, R14, R15, R16, respectively. It should beunderstood, however, that in some embodiments the link-fiber interfaceof the optical module 100 may not have an equal number of transmitoptical fiber connectors T and receive optical fiber connectors R.

The laser light supply system 101 is configured to output the Nwavelengths of laser light at each laser output port with controlledpolarization. It is of interest to maintain this controlled polarizationof the laser light at the laser input optical ports of the chips103A-103D. Therefore, the optical fibers L1-L16 that connect the laserinput optical ports of the chips 103A-103D to the laser output ports ofthe laser light supply system 101 are polarization maintaining (PM)optical fibers (PMF's) that are configured to maintain a linearpolarization of the laser light as the laser light travels through thePMF. Examples of PMF include PANDA PM Specialty Optical Fiber byCorning, Inc., and “bow-tie” style PMF-633-B1 by Coherent, Inc. Itshould be understood that that the optical fiber L1-L16 can beessentially any type of polarization maintaining fiber. However, asdisclosed herein, a plurality of the optical fibers L1-L16 can beincluded within a PMF ribbon, where the mechanical structure of the PMFribbon helps maintain a fixed orientation, i.e., polarizationorientation, of each PMF along the length of the PMF ribbon. In thismanner, the polarization orientation of each PMF within the PMF ribbonis fixed and known at each location along the length of the PMF ribbon.

The PMF's (L1-L16) include birefringence-inducing members that areconfigured to create a biaxial stress field in the core of the PMF. Thebiaxial stress field creates birefringence, such that at one orientationabout the axis of the core there is one index of refraction, and atanother orientation about the axis of the core there is another index ofrefraction. A feature of the birefringence is that when linear polarizedlight is transmitted into the core of the PMF in alignment to thebirefringence field, the linear polarized light will remain linearpolarized in alignment to the birefringence field as it travels throughthe PMF. In this manner, the PMF can be used to direct linear polarizedlight that is output by the laser light supply system 101 into the chip103A-103D without changing the linear polarization of the light. And,the PMF is oriented at the chip 103A-103D so that the polarized lightemitted from the PMF is properly aligned with the optical gratingcoupler on the chip 103A-103D so as to maintain linear polarization ofthe light as it enters the chip 103A-103D.

In contrast to the optical fibers L1-L16, the optical fibers T1-T16 thatconnect the transmit optical ports of the chips 103A-103D to thetransmit optical fiber connectors T at the link-fiber interface are notpolarization maintaining. In some embodiments, each of the opticalfibers T1-T16 is a single mode fiber (SMF). Also, the optical fibersR1-R16 that connect the receive optical ports of the chips 103A-103D tothe receive optical fiber connectors R at the link-fiber interface arenot polarization maintaining. In some embodiments, each of the opticalfibers R1-R16 is an SMF. The use of optical fibers T1-T16 and R1-R16that are not polarization maintaining for the transmit and receiveoptical connections between the chips 103A-103D and the link-fiberinterface avoid possible adverse polarization dispersion effects.

In some embodiments, the optical module 100 can be included as part of asystem-on-chip (SOC) data communication system. In the SOC datacommunication system, or other system, the optical module 100 can bereferred to as a “package.” However, for description purposes, the termoptical module 100 is used herein rather than “package.” In someembodiments, the optical module 100 can be configured for use as anoptical switch, with the chips 103A-103D connected by electrical linksto an application-specific-integrated-circuit (ASIC). It should beunderstood, however, that the optical module 100 can be configured formany different uses in different applications.

During operation of the optical module 100, optical power, i.e., laserlight, is generated by the laser light supply system 101 and istransmitted through the optical fibers L1-L16 to the chips 103A-103D.The laser light is modulated by the chips 103A-103D to encode digitaldata as modulated light. The modulated light is transmitted from thechips 103A-103D through the optical fibers T1-T16 to the link-fiberinterface for transmission to an optical communication network. Also,modulated light that is received at the link-fiber interface from theoptical communication network is transmitted through the optical fibersR1-R16 to the chips 103A-103D for demodulation to determine the digitaldata encoded within the received modulated light.

It should be understood that the laser light supply system 101 mayencounter challenges with operation at high temperatures, such asreduced reliability and/or reduced efficiency. Therefore, in someembodiments, the laser light supply system 101 is sufficiently separatedfrom the chips 103A-103D within the optical module 100 to allow adequatethermal management. In some embodiments, a gain medium of the laserlight supply system 101 is not directly bonded to the chips 103A-103Dand is not located within a minimum specified distance from the chips103A-103A or from an ASIC to which the chips 103A-103D are connected. Insome embodiments, the minimum specified distance is about 1 centimeter.However, it should be understood that in various embodiments, theminimum specified distance may be less than or greater than about 1centimeter, depending on the thermal output of the chips 103A-103D andthe thermal management capability of the laser light supply system 101and the thermal management capability of the optical module 100. Also,while the example of FIG. 1 has the laser light supply system 101installed within the optical module 100, it should be understood that inother embodiments, the laser light supply system 101 can be locatedoutside of the optical module 100, with the optical fibers L1-L16configured to carry the laser light from the laser light supply system101 into the optical module 100 and to the chips 103A-103D.

FIG. 2 shows a diagram of how a fiber set 200 is used to connect thechip 103A-103D to the laser light supply system 101 and the link-fiberinterface, in accordance with some embodiments. Within the opticalmodule 100, the fiber set 200 includes three optical fibers:

1) one PMF (one of L1-L16) connecting one laser output port of the laserlight supply system 101 to one laser input optical port of the chips103A-103D,

2) one SMF (one of T1-T16) connecting one transmit optical port of thechips 103A-103D to one transmit optical fiber connector T at thelink-fiber interface, and

3) one SMF (one of R1-R16) connecting one receive optical fiberconnector R at the link-fiber interface to one receive optical port ofthe chips 103A-103D.

The fiber set 200 includes an optical fiber 201 to connect one laseroutput port of the laser light supply system 101 to one laser inputoptical port of the chips 103A-103D. In the optical module 100 of FIG.1, the optical fiber 201 is one of the optical fibers L1-L16. Theoptical fiber 201 is a PMF. The fiber set 200 also includes an opticalfiber 203 to connect one transmit optical port of the chips 103A-103D toone transmit optical fiber connector T at the link-fiber interface. Inthe optical module 100 of FIG. 1, the optical fiber 203 is one of theoptical fibers T1-T16. The optical fiber 203 is an SMF (not polarizationmaintaining). The fiber set 200 also includes an optical fiber 205 toconnect one receive optical fiber connector R at the link-fiberinterface to one receive optical port of the chips 103A-103D. In theoptical module 100 of FIG. 1, the optical fiber 205 is one of theoptical fibers R1-R16. The optical fiber 205 is an SMF (not polarizationmaintaining).

The laser input optical port of the chip 103A-103D includes an opticalcoupler 207 for receiving the laser light from the optical fiber 201.Because polarization of the light from the laser light supply system 101to the chip 103A-103D is controlled by the optical fiber 201 being aPMF, the optical coupler 207 can be a single-polarization opticalcoupler. Also, the transmit optical port of the chip 103A-103D includesan optical coupler 209 for transmitting the modulated light (modulatedto encode digital data) from the chip 103A-103D to the transmit opticalfiber connector T at the link-fiber interface. Because the polarizationof the modulated light transmitted from the chip 103A-103D to thetransmit optical fiber connector T is controlled, the optical coupler209 can be a single-polarization optical coupler. Also, the receiveoptical port of the chip 103A-103D includes an optical coupler 211 forreceiving modulated light from the receive optical fiber connector R atthe link-fiber interface. Because the modulated light received at thelink-fiber interface is not polarization-controlled, the optical coupler211 is a polarization-diverse optical coupler. It should be appreciatedthat the chips 103A-103D within the optical module 100 use bothsingle-polarization optical couplers 207 and 209, andpolarization-diverse optical couplers 211. In some embodiments, theoptical couplers 207, 209, 211 are vertical couplers, which provide moreflexibility in chip layout and more direct wafer-level testing. In someembodiments, the optical couplers 207, 209, 211 are vertical gratingcouplers compatible with high-volume manufacturing, e.g., zero-changeCMOS.

Because the two optical couplers 207 and 209 for a given fiber set 200can be single-polarization optical couplers, and just the one opticalcoupler 211 for the given fiber set 200 is a polarization-diverseoptical coupler, cost is reduced and loss of light power within theoptical module 100 is reduced. Loss of light power within the opticalmodule 100 can require increased expense for optical amplifiers. Also,loss of light power within the optical module 100 can cause limitationson data capacity and bandwidth. There is a system tradeoff related topolarization-dependence of the optical couplers 207, 209, 211. Morespecifically, single-polarization optical couplers, such as 207 and 209,have lower loss of light power and lower chip footprint (which reducescost). Therefore, it is beneficial to control polarization of lightinputs to the chip 103A-103D at locations/interfaces external to thechip 103A-103D, with possible use of PMF to carry thepolarization-controlled light to the chip 103A-103D. However, control oflight polarization at too many locations/interfaces external to the chip103A-103D can impose an unacceptable restriction on the larger systemdesign. Therefore, it is useful to control light polarization throughpackaging at as many locations/interfaces external to the chip 103A-103Das possible, while providing polarization-diverse optical couplercapability at some limited number of chip interfaces.

In some embodiments, the chips 103A-103D are configured to includewavelength-division multiplexing (WDM) multiplexing and de-multiplexingfunctionality, resonant modulators, and resonant detectors. For example,FIG. 2 shows that the chip 103A-103D includes an optical waveguide 215configured to carry incoming laser light from the optical coupler 207through/near resonant modulators 213, which function to modulate thelaser light to encode digital data. The modulated laser light istransmitted through the optical waveguide 215 to the optical coupler 209for transmission through the optical fiber 203 to the transmit opticalfiber connector T of the link-fiber interface. FIG. 2 also shows thatthe chip 103A-103D includes an optical waveguide 219 configured to carryincoming modulated laser light from the optical coupler 205 through/nearresonant detectors 217, which function to detect and de-modulate thelaser light to obtain digital data encoded within the incoming modulatedlaser light.

As light travels through a complete communications link, the lightpasses through the three optical couplers 207, 209, 211 on the chip103A-103D. The light travels from the off-chip laser light supply system101 through the optical coupler 207 to the on-chip resonant modulators213. The light travels from the on-chip resonant modulators 213 throughthe optical coupler 209 to the link-fiber interface. The light travelsfrom the link-fiber, i.e., network, through the link-fiber interfacethrough the optical coupler 211 to the resonant detectors 217.

It is desired that all components within the optical link between thelaser light supply system 101 and the chip 103A-103D (such as opticalfiber, groove arrays, optical connectors, etc.) maintain polarization ofthe laser light as emitted from the laser light supply system 101. Asmentioned above, it is useful to provide a polarization maintainingoptical fiber between the laser light supply system 101 and the chip103A-103D, since this optical fiber is short and the laser light alreadyhas a well-defined polarization. This allows the optical coupler 207 tobe a single-polarization optical coupler.

It is desired that components within the optical links between the chip103A-103D and the link-fiber interface (such as optical fibers, groovearrays, optical connectors, etc.) provide low PMD. The optical fibersused to connect the chip 103A-103D to the link-fiber interface (linkfibers) are not polarization maintaining, because use of polarizationmaintaining optical fiber for the link fibers adds to total system cost,and may increase loss of light power, and may increase polarization modedispersion (PMD), and may complicate standard fiber operations, such assplicing.

In optical connections that are intended to be polarization maintaining,such as between the laser light supply system 101 and the chip103A-103D, polarization maintenance can be provided through use of PMF,and also by management of bend and twist induced perturbations, withparticular attention to the symmetry of these perturbations with respectto the polarization axis. Generally, any portions of fiber longer than afew centimeters that cannot be carefully bend-managed should be PMF inorder to achieve polarization control in the optical connection.However, a connection may include short sections of non-PMF, especiallyif these short sections of non-PMF are enclosed or otherwise protectedfrom perturbations.

In optical connections that are not intended to be polarizationmaintaining and/or require low PMD, such as between the chip 103A-103Dand the link-fiber interface, PMF should be avoided or segments of PMFshould be kept short enough to contribute acceptable PMD. In someconfigurations, acceptable PMD implies that all of the WDM channels areat substantially the same polarization. If all WDM channels fall withinfrequency difference Δf (e.g., about 1 TeraHertz (THz) of a nominalfrequency, the total PMD (tPMD) satisfy the relationship: tPMD<<(1/Δf).For example, acceptable PMD should be much less than 1 picosecond, andso even moderate-lengths of PMF should be avoided. For example, thelength of PMF used in an optical connection that is not intended to bepolarization maintaining and/or requires low PMD should be less than orequal to about 10 centimeters.

FIG. 3 shows a diagram of how four fiber sets 200A, 200B, 200C, 200D areconnected to a given one of the chips 103A-103D, in accordance with someembodiments. It should be understood that while the example embodimentof FIG. 1 shows four fiber sets 200A, 200B, 200C, 200D connected to eachone of the chips 103A-103D, in various embodiments, any chip 103A-103Dwithin the optical module 100 can be configured to connect with one ormore fiber set(s) 200. And, it should be understood that connection ofmore fiber sets 200 to a given chip 103A-103D leverages the cost of thelaser light supply system 101 over more data communication channels.

The optical module 100 is scalable to ultra-high capacity and isdesigned for low-cost manufacturing, where capacity can be representedby number of communication channels, i.e., number of transmit/receiveports in the link-fiber interface. Optical fibers within the opticalmodule 100 may be vertically butt-coupled to the chip 103A-103D, butwill preferably be packaged with optical fibers horizontal to the chip103A-103D so that fiber-to-chip connection is more mechanically stable,resistant to external forces, vibrations, etc. Here horizontal is usedto mean parallel to the plane of the fabrication layers of the chip103A-103D. Also, an optical fiber may be considered vertical if the axisof the optical fiber is more than 45 degrees off of the plane of thechip 103A-103D. In some embodiments, the optical fibers aresubstantially horizontal, but light is redirected into a vertical beamaligned with vertical optical couplers on the chip 103A-103D, such aswith optical couplers 207, 209, 211. Light may be redirected by a prismor angle-cleave, and the reflecting surface may further include coatings(e.g., dielectric or metallic) or a gap designed to improve opticalcoupling efficiency and manufacturability. Turning the optical beamallows a mechanically robust package (optical fibers are horizontal)while still providing the vertical beam needed for optical gratingcouplers on the chips 103A-103D.

FIG. 4A shows a lens assembly 4200 for use in attaching an optical fiberto the chip 103A-103D in a parallel-coupled configuration, in accordancewith some embodiments of the present invention. In some embodiments, thelens assembly 4200 is a type of GRIN assembly that can be mated with agrating array that is physically addressed to the chip 103A-103D. Insome embodiments, the lens assembly 4200 can be aligned with the gratingarray in a single alignment step to provide acceptable alignment of thelight output from the lens assembly 4200 with the optical gratingcoupler on the chip 103A-103D. In various embodiments, use the lensassembly 4200 in combination with the grating array provides forpassive/rough alignment of optical fibers with the optical couplers onthe chip 103A-103D.

The lens assembly 4200 includes four regions: 1) a single mode fiber(SMF) 4240 region, 2) an optical gap structure 4230 region, 3) amulti-mode optical fiber (MMF) 4220 (graded index MMF) region, and 4) anoptical end structure 4210 region. The optical end structure 4210 isoptional. In some embodiments, the outer diameters of the optical endstructure 4210, the MMF 4220, the optical gap structure 4230, and theSMF 4240 are similar. If the outer diameters of the optical endstructure 4210, the MMF 4220, the optical gap structure 4230, and theSMF 4240 are similar, or approximately the same, it allows the opticalend structure 4210, the MMF 4220, the optical gap structure 4230, andthe SMF 4240 to be fusion spliced using commercially available equipmentand leads to better alignment of the light beam with the center of thelens assembly 4200, including with the center of the SMF 4240. In anexample embodiment, the outer diameter of each of the optical endstructure 4210, the MMF 4220, the optical gap structure 4230, and theSMF 4240 is approximately 125 micrometers (μm). However, it should beunderstood that in other embodiments the outer diameter of each of theoptical end structure 4210, the MMF 4220, the optical gap structure4230, and the SMF 4240 can be either less than or greater than 125 μm.

In some embodiments, the optical gap structure 4230 is a coreless fiber.For example, in some embodiments, the optical gap structure 4230 is a125 μm outer diameter coreless/acrylate termination optical fiber, suchas that provided by the company OFS as their Item No. F15330, by way ofexample. It should be understood, however, that in other embodiments theoptical gap structure 4230 can be another type of coreless fiber. Also,in some embodiments, the optical gap structure 4230 is a step-index MMF.For example, in some embodiments, the optical gap structure 4230 is a 50μm core diameter/125 μm outer diameter step-index MMF, such as thatprovided by Prysmian Group as DrakaElite Specialty Fiber—RadHard 50 μmStep-Index Multimode Fibre, by way of example. It should be understood,however, that in other embodiments the optical gap structure 4230 can beanother type of MMF.

In some embodiments, the lens assembly 4200 does not include the opticalend structure 4210. In some embodiments, the optical end structure 4210can be a region filled with epoxy or other polymer approximatelyindex-matched to the MMF 4220. In other embodiments, the MMF 4220 can becleaved normal to the surface (i.e., substantially perpendicular to theaxis of the lens assembly 4200) or at an angle (i.e., at an anglerelative to the axis of the lens assembly 4200) if a lateral beam isdesired. However, in some embodiments, the optical end structure 4210 ispresent and is cleaved normal to the axis of the lens assembly 4200. Insome embodiments, the optical end structure 4210 is present and iscleaved at an angle relative to the axis of the graded index MMF 4220,or the optical gap structure 4230, or the SMF 4240. With an appropriatecleave, the optical end structure 4210 functions as a turning prism forthe light that it receives from the graded index MMF 4220. FIG. 4B showsan example cleaving of the optical end structure 4210 with exampleangles, in accordance with some embodiments of the present invention.

In some embodiments, the end-face of the optical end structure 4210(i.e., the face opposite of the graded index MMF 4220) is coated with ametallic mirror or a dielectric mirror. In some embodiments where thecoating on the end-face of the optical end structure 4210 is adielectric mirror, the coating can include a layered stack, enablingbroadband reflection. Also, in the embodiments where the end-face of theoptical end structure 4210 is coated with the mirror, the end-face willcontinue to function as the mirror when it is coated with an opticalindex matching epoxy.

In some embodiments of the lens assembly 4200, the MMF 4220 is a gradedindex MMF. For example, in some embodiments, the MMF 4220 is a 62.5 μmcore diameter/125 μm outer diameter acrylate silica fiber, such as thatprovided by the company OFS as their Item No. BF04431-01, by way ofexample. It should be understood, however, that in other embodiments theMMF 4220 can be another type of graded index MMF.

In some example embodiments, the SMF 4240 is an optical fiber such asSMF-28 Ultra Optical Fiber provided by the company Corning, by way ofexample. In some example embodiments, the SMF 4240 is compliant with theITU-T G.652 standard. In some example embodiments, the SMF 4240 is aPolarization Maintaining Fiber (PMF). For example, in some embodimentswhere the SMF 4240 is a PMF, the birefringent axes can be alignedrelative to the cleaved angle of the optical end structure 4210, ifpresent. For example, the slow axis of the PMF can be aligned at 0°,90°, or at any arbitrary angle relative to the major axis of the cleaveof the optical end structure 4210, if present. In some exampleembodiments, the SMF 4240 is a PANDA optical fiber provided by thecompany Corning, by way of example. Additionally, in some embodiments,multiple SMF's 4240 and corresponding lens assemblies 4200 are attachedto the chip 103A-103D in the parallel-coupled configuration with themultiple SMF's 4240 configured as an optical fiber array/ribbon. Inthese optical fiber array/ribbon embodiments, the multiple SMF's 4240can be any combination of optical fibers, such as SMF-28 Ultra OpticalFiber and PANDA optical fiber, by way of example, as well as any othertype of SMF 4240.

FIG. 4C shows an interface of eight instances of the lens assembly 4200(e.g., 4200-1 through 4200-8) with the chip 103A-103D, in accordancewith an example embodiment of the present invention. In someembodiments, the chip 103A-103D can include one or more vertical gratingcouplers, such as optical couplers 207, 209, 211 to enable opticalconnection with one or more optical fibers. In some embodiments,individual lens assemblies 4200 can be connected to the chip 103A-103D.However, in some embodiments, multiple instances of the lens assembly4200 (e.g., 4200-1 through 4200-8) can be connected to the chip103A-103D. In these embodiments, multiple SMF's 4240 can be configuredas an optical fiber ribbon assembly. For example, FIG. 4C shows an arrayof eight optical fibers 4610-1 through 4610-8 connected to the chip103A-103D, where the optical fibers 4610-1 through 4610-8 correspond tothe SMF's 4240. Each optical fiber 4610-1 through 4610-8 has acorresponding one of the eight lens assemblies 4200-1 through 4200-8. Inthese embodiments, after the polymer jacket (coating over the claddingof the SMF's) is removed (as part of the cleaving operation), the cleaveand splice operation can continue in parallel (i.e., as ribbonassemblies). Therefore, it should be understood that multiple instancesof the lens assembly 4200 as described above can be simultaneouslyformed in a ribbon-like manner to accommodate multiple SMF 4240 fibers.In some example embodiments, a number of the multiple SMF 4240 fibersaccommodated by multiple instances of the lens assembly 4200 formed inthe ribbon-like manner is 2, 4, 8, 12, 16, or 24. However, in otherembodiments, any number of the multiple SMF 4240 fibers can beaccommodated by a corresponding number of multiple instances of the lensassembly 4200 formed in the ribbon-like manner. Also, as additionaloptical fiber ribbons become commercially available, the number of themultiple SMF 4240 fibers accommodated by the corresponding number ofmultiple instances of the lens assembly 4200 formed in the ribbon-likemanner will increase.

FIG. 4C shows a region 4620 where the silicon has been thinned. For SOI(silicon-on-insulator) wafers, the handle silicon can be etched down tothe buried oxide (BOX). For bulk CMOS wafers, the backside silicon canbe etched down to the shallow trench isolation. The specific pattern ofthe region 4620 can be adjusted lithographically. In FIG. 4C, the region4260 includes a number of ridges 4630. These ridges 4630 help to alignthe optical fibers 4610-1 through 4610-8 to the vertical coupler on thechip 103A-103D. The ridges 4630 can have any shape, so long as they donot interfere with the placement of the optical fibers 4610-1 through4610-8. For example, in various embodiments, the ridges 4630 can beV-shaped (to form V-grooves), posts, or completely absent. In someembodiments, the optical fibers 4610-1 through 4610-8 are epoxied to thechip 103A-103D within the region 4620. If the end face of the opticalend structure 4210 is not coated, then it is necessary for the end faceto remain free of index matched epoxy. However, if the end face of theoptical end structure 4210 is coated with a reflective material, thenthe optical end structure 4210 can be submerged in epoxy.

FIG. 4D shows a top-down view of the chip 103A-103D of FIG. 4C, inaccordance with some embodiments of the present invention. FIG. 4E showsDetail E of FIG. 4D, in accordance with some embodiments of the presentinvention. In some embodiments, the angle of the optical end structure4210 is cleaved so that the light propagation turns towards the chip103A-103D. For example, if the chip 103A-103D has a vertical couplerwith an angle of acceptance of 14° from normal, then the end region 4210should be cleaved such that the light propagates at an angle of 14° froma reference direction perpendicular to the plane of the chip 103A-103D.

With reference back to FIG. 4B, the relationship between the tilt angleof the grating and the angle of the cleave is shown. For a grating tiltangle, the angle between the optical fiber axis and the cleave normalshould be (90°—tilt angle)/2. For example, for the counter-propagatingconfiguration shown in FIG. 4B, a cleave angle of about 38° is suitablefor a grating tilt angle of about 14°. For a co-propagatingconfiguration, the same formula applies, for example a cleave angle ofabout 52° would be suitable for a grating tilt angle of about −14°. Invarious embodiments, the grating tilt angle can be either positive ornegative. In some example embodiments, the absolute value of the gratingtilt angle is within the range extending from about 10° to about 25°.However, in other embodiments, the grating tilt angle can be less thanabout 10°, or greater than about 25°.

FIG. 5A shows a vertical cross-section through a connector 104A of thechip 103A, corresponding to View A-A as shown in FIG. 1, in accordancewith some embodiments. The connector 104A is formed to have grooves forassisting with and passively controlling alignment of the optical fibersL1-L4, T1-T4, and R1-R4 to corresponding optical ports on the chip 103A.The example connector 104A in FIG. 5A shows use of “V” grooves, whichcan be produced through anisotropic etching of crystalline materials insome example embodiments. Groove arrays, such as shown in FIG. 5A, maybe directly etched into the chip 103A or into an additional substrateblock that is addressed, i.e., spatially aligned, to the chip 103A. FIG.5A shows that the four optical fibers L1-L4 (PMF) are positioned next toeach other, and the optical fibers T1-T4 (SMF) and R1-R4 (SMF) arepositioned next to each other. The positions of the various opticalfibers within the connector 104A is determined in part by theconfiguration of the chip 103A. Also, a particular arrangement of theoptical fibers (PMF vs. SMF and/or laser vs. transmit vs. receive)across the connector 104A is driven primarily by chip 103A designconsiderations.

FIG. 5B shows a vertical cross-section through a connector 104B of thechip 103B, corresponding to View B-B as shown in FIG. 1, in accordancewith some embodiments. As with the connector 104A, the connector 104Balso has a “V” grooves for assisting with and passively controllingalignment of the optical fibers L5-L8, T5-T8, and R5-R8 to correspondingoptical ports on the chip 103B. FIG. 5B shows that the four opticalfibers L5-L8 (PMF) are positioned next to each other, and the opticalfibers T5-T8 (SMF) and R5-R8 (SMF) are positioned next to each other.The positions of the various optical fibers within the connector 104B isdetermined by the configuration of the chip 103B. Also, a particulararrangement of the optical fibers (PMF vs. SMF and/or laser vs. transmitvs. receive) across the connector 104B is driven primarily by chip 103Bdesign considerations.

FIG. 5C shows a vertical cross-section through a connector 104C of thechip 103C, corresponding to View C-C as shown in FIG. 1, in accordancewith some embodiments. As with the connector 104A, the connector 104Calso has a “V” grooves for assisting with and passively controllingalignment of the optical fibers L9-L12, T9-T12, and R9-R12 tocorresponding optical ports on the chip 103C. FIG. 5C shows that thefour optical fibers L9-L12 (PMF) are separated from each other by two ofthe optical fibers T9-T12 (SMF) and R9-R12 (SMF). The positions of thevarious optical fibers within the connector 104C is determined by theconfiguration of the chip 103C. Also, a particular arrangement of theoptical fibers (PMF vs. SMF and/or laser vs. transmit vs. receive)across the connector 104C is driven primarily by chip 103C designconsiderations. Having an interleaved arrangement ofpolarization-maintaining optical fibers (e.g., L9-L12) andnon-polarization-maintaining optical fibers (e.g., T9-T12 and R9-R12)can have advantages for chip (e.g., 103C) layout in that each laserinput optical coupler 207 on the chip can be in close proximity to thecorresponding transmit optical coupler 209 and the corresponding receiveoptical couplers 211 on the chip.

FIG. 5D shows a vertical cross-section through a connector 104D of thechip 103D, corresponding to View D-D as shown in FIG. 1, in accordancewith some embodiments. As with the connector 104A, the connector 104Dalso has a “V” grooves for assisting with and passively controllingalignment of the optical fibers L13-L16, T13-T16, and R13-R16 tocorresponding optical ports on the chip 103D. FIG. 5D shows that thefour optical fibers L13-L16 (PMF) are separated from each other by twoof the optical fibers T13-T16 (SMF) and R13-R16 (SMF). The positions ofthe various optical fibers within the connector 104D is determined bythe configuration of the chip 103D. Also, a particular arrangement ofthe optical fibers (PMF vs. SMF and/or laser vs. transmit vs. receive)across the connector 104D is driven primarily by chip 103D designconsiderations.

In FIGS. 5A-5D, polarization-maintaining connections are depictedschematically as PANDA-type PMF (with stress rods aligned along theshort dimension of the ribbon, i.e., vertically in the figures). But, ingeneral, the polarization-maintaining connections within the connectors104A-104D may include other types of fiber including short orbend-managed sections of non-polarization-maintaining fiber. As depictedin the connectors 104A and 104B, the polarization-maintainingconnections may be grouped together (separated from the data channels).In some embodiments, laser and data link connections may be grouped bywhich chip 103A-103D they connect to (with any permutation that may besuitable for connecting to the chip 103A-103D).

If a polarization-maintaining optical connection is formed using PMF, itis required that the PMF be orientation-aligned at thepolarization-maintaining optical connection, so that the polarizationaxis of the light remains well-aligned with the axis of PMF throughoutthe system to avoiding polarization crosstalk. Orientation alignment ofthe PMF can be achieved in several ways. In some embodiments, each PMFcan be rotated while monitoring an orientation-dependent feedback signal(visual, optical transmission, etc.). When the orientation-dependentfeedback signal indicates proper orientation alignment of the PMF, theorientation of the PMF can be fixed, such as by tacking the fiber to asubstrate. This approach introduces a manufacturing cost proportional tothe number of PMF's that must be orientation-aligned.

In some embodiments, multiple PMF can be put together in a ribbonstructure, i.e., as a PMF ribbon, such that a birefringent axis of eachindividual PMF is substantially aligned along a long dimension of theribbon structure. Such a PMF ribbon could be produced through feedbackcontrol of the orientation of each PMF during production of the PMFribbon. Also, in some embodiments, each PMF can be produced with amechanical feature, e.g., flat surface, that assists with orientationcontrol of the PMF during spooling of the PMF, e.g., during fiber draw,or during PMF ribbon production. PMF with such mechanical features canbe mass-produced, e.g., by grinding a flat in the preform from which thePMF is drawn. In this case feedback control of the orientation of eachPMF may not be needed to produce an oriented PMF ribbon. Chip andconnector arrangements where multiple PMF's are adjacently positioned,such as in connectors 104A and 104B for chips 103A and 103B,respectively, have an advantage in that the multiple PMF's can be formedintegrally within the PMF ribbon and maintain the structuralconfiguration of the PMF ribbon to the connector 104A/104B at the chip103A/103B, which helps with alignment of the multiple PMF's at the chip103A/103B. Also, in some embodiments, a quasi-PM fiber ribbon can beproduced by arranging a ribbon of non-polarization-maintaining fibers soas to induce birefringence. The birefringence in the quasi-PM fiberribbon may be substantially smaller than that of typical commercial PMF,particularly when the length and perturbations of the quasi-PM fiberribbon can be managed.

FIG. 5E shows a SQUID assembly 500, in accordance with some embodiments.The SQUID assembly 500 is a connectorized sub-assembly that enablesalignment of optical fiber connections, such as within the opticalmodule 100, and facilitates testing and manufacturing of optical fiberconnections and associated optical systems. In the example SQUIDassembly 500, a connector 501 is configured to align, interface, andconnect/attach with the connector 104A of the chip 103A. It should beunderstood, however, that in various embodiments, the connector 501 ofthe SQUID assembly 500 can be configured to align, interface, andconnect/attach with either of the connectors 1048, 104C, 104C, or anyother type of chip connector. It should be understood that the connector501 maintains a fixed physical position and fixed orientation of each ofthe four PMF's L1-L4. In this manner, the connector 501 maintains apolarization alignment of each of the four PMF's L1-L4 in a knownorientation that matches a polarization alignment of correspondingoptical fibers and/or optical waveguides within the connector 104A towhich the connector 501 is intended to connect. Also, the connector 501in the example of FIG. 5E has the four PMF's L1-L4 positionedside-by-side within the connector 501. This allows the four PMF's L1-L4to be formed within a PMF ribbon in some embodiments. Therefore, in someembodiments, a PMF ribbon 507 can be attached to the connector 501 ofthe SQUID assembly 500. However, it should be understood that in someembodiments the four PMF's L1-L4 can be individually articulatablePMF's, i.e., not part of a common multi-PMF structure, such as a PMFribbon or the like, at respective insertion locations on the connector501.

The SQUID assembly 500 also includes a connector 503 configured toconnect to a connector 102 of the laser light supply system 101. Theconnector 503 in the example of FIG. 5E has the four PMF's L1-L4positioned side-by-side within the connector 503. It should beunderstood that the connector 503 maintains a fixed physical positionand fixed orientation of each of the four PMF's L1-L4. In this manner,the connector 503 maintains a polarization alignment of each of the fourPMF's L1-L4 in a known orientation that matches a polarization alignmentof corresponding optical fibers and/or optical waveguides within theconnector 102 of the laser light supply system 101 to which theconnector 503 is intended to connect. Also, the connector 503 in theexample of FIG. 5E has the four PMF's L1-L4 positioned side-by-sidewithin the connector 503. This allows the four PMF's L1-L4 to be formedwithin a PMF ribbon in some embodiments. Therefore, in some embodiments,the PMF ribbon 507 can be attached to the connector 503 of the SQUIDassembly 500. In some embodiments, a multicore optical fiber can be madeso that the birefringent axis of the polarization-maintainingconnections has a predictable orientation. For example, a multicoreoptical fiber can be made to have an outer flat or as a ribbon-likeoptical fiber with multiple cores in a line, with stress elementsinducing a birefringent axis along the flat or ribbon's long axis. Also,in some embodiments, a birefringent axis can be induced radially.However, it should be understood that in some embodiments the four PMF'sL1-L4 can be individually articulatable PMF's, i.e., not part of acommon multi-PMF structure, such as a PMF ribbon or the like, atrespective insertion locations on the connector 503.

The SQUID assembly 500 also includes connectors 505A, 505B, 505C, 505Dthat are each configured to connect to the link-fiber interface of theoptical module 100. In some embodiments, the connectors 505A, 505B,505C, 505D actually function as the transmit/receive optical fiberconnectors (T/R) of the link-fiber interface. In some embodiments, theconnectors 505A, 505B, 505C, 505D are duplex-type optical connectors,such as LC, FC, SC, or essentially any other type of optical connector.The non-polarization-maintaining optical fibers in the SQUID assembly500, e.g., T1-T4 and R1-R4, can be terminated at the connectors 505A,505B, 505C, 505D to form the link-fiber interface that is exposed on theexterior surface of the optical module 100. In the example SQUIDassembly 500 of FIG. 5E an SMF extends between the connector 501 and theconnectors 505A-505D for each transmit and receive optical dataconnection. Specifically, separate SMF's T1-T4 and R1-R4 are providedfor the respective optical data connections.

Deployment of the optical module 100 can include plugging link-fibercables with compatible duplex connectors into the connectors 505A-505Dat the exterior surface of the optical module 100. In this manner, thetransmit fiber of one optical module 100 can be connected through thelink fiber to the receive fiber of another optical module 100, andvice-versa. For higher-bandwidth connections, the connectors 505A-505Dmay include more than two optical fibers, fiber ribbons, a multicorefiber, and/or a tapered fiber bundle.

In some embodiments the SMF's T1-T4 and R1-R4 can be individuallyarticulatable SMF's, i.e., not part of a common multi-PMF structure,such as a PMF ribbon or the like. However, in some embodiments, multipleones of the SMF's T1-T4 and R1-R4 can be included together within acommon multi-SMF structure, such as an SMF ribbon or the like. Forexample, the example SQUID assembly 500 of FIG. 5E shows the SMF's T1and R1 formed together within an SMF ribbon 509. Also, the SMF's T2 andR2 are formed together within an SMF ribbon 511. And, the SMF's T3 andR3 are formed together within an SMF ribbon 513. And, the SMF's T4 andR4 are formed together within an SMF ribbon 515. While the example SQUIDassembly 500 of FIG. 5E includes four SMF ribbons 509, 511, 513, 515, itshould be understood that in various embodiments the SQUID assembly 500can include any number of SMF ribbons, microcables, and/or multi-coreoptical fibers as needed to make the optical data connections betweenthe connector 501 and the connectors of the link-fiber interface, e.g.,connectors 505A-505D. Also, in various embodiments, the SMF ribbonshaving more than two cores can be used in the SQUID assembly 500 to makethe optical data connections between the connector 501 and theconnectors (T, R) of the link-fiber interface. It should be understoodthat microcables and/or optical fiber ribbons in the SQUID assembly 500can be configured to provide a fiber-management solution and may providesome protection and control of bend and twist seen by the opticalfibers.

The connector 501 of the SQUID assembly 500 can have differentarrangements of positions of laser-connections (e.g., L1-L4) and datalink connection channels (e.g., T1-T4 and R1-R4) to accommodatedifferent corresponding arrangements in the connectors 104A-104D of thechips 103A-103D, such as shown in FIGS. 5A-5D, in order to balance theneeds of chip 103A-103D layout and facilitate manufacturing of the SQUIDassembly 500, and/or satisfy other layout and fabrication requirements.

In some embodiments, positioning of the laser connection optical fibers(e.g., L1-L4) adjacent to each other in the connector 501 can facilitatemanufacturing of the SQUID assembly 500 and may provide improvedpolarization extinction ratio (PER) of the polarization maintainingconnections. With the laser connection optical fibers (e.g., L1-L4)positioned adjacent to each other in the connector 501, the physicalorientation of the polarization axis of the laser connection opticalfibers (e.g., L1-L4) can be more easily controlled.

FIG. 6 shows a diagram of how the SQUID assembly 500 can be connected toa chip, in accordance with some embodiments. The example of FIG. 6 showsthe connector 501 of the SQUID assembly 500 connected to the connector104A of the chip 103A. In some embodiments, SMF can be used inside theconnector 104A of the chip 103A, even for connections where polarizationis to be maintained, because the orientation of the SMF can be tightlycontrolled within the connector 104A over the short length of the SMFthat is present inside the connector 104A. For example, FIG. 6 shows aregion 601 where SMF is used for the polarization-maintainingconnections associated with optical connection of the chip 103A to thelaser light supply system 101, i.e., associated with PMF's L1-L4. And,FIG. 6 shows a region 605 indicating that all 12 optical fibers withinthe connector 104A can be SMF. Use of SMF inside the connector 104A ofthe chip 103A can make manufacturing easier because alignment of the SMFis not required inside the connector 104A, whereas controlled alignmentof PMF would be required if PMF were used inside the connector 104A.Also, SMF is less expensive than PMF. So, overall cost and manufacturingtime can be reduced by using SMF inside the connector 104A of the chip103A, as opposed to using PMF, so long as the polarization orientationof the SMF is carefully controlled within the connector 104A for thepolarization-maintaining connections. It should be understood that theSMF used in the connector 104A of the chip 103A can be essentially anytype optical fiber that is not PMF and that has a high polarizationextinction ratio (PER), such that the polarization does not wander inthe SMF within the connector 104A.

In some embodiments, the connector 104A is a connectorized beam-turningassembly, such as depicted by a region 603. In some embodiments, theconnector 104A can include a graded-index (GRIN) region to provideoptical lensing, such as the MMF 4220, in which case the connector 104Acan be considered a type of GRIN array assembly. The connector 104A is a3×N connector, in that the connector 104A provides for connection of Nfiber sets 200, and therefore includes 3×N optical fiber connections. Inthe example of FIG. 6, the connector 104A accommodates N=4 fiber sets,and therefore includes 12 optical fiber connections. In someembodiments, the connector 104A can include additional optical fiberconnections beyond the 3×N optical fiber connections to accommodateconnection of spare optical fibers, and/or optical fibers carryingauxiliary signals, and/or optical fibers for other purposes. Forexample, a connector 104A designated as 3×N+1 is configured to providefor connection of N fiber sets 200 and 1 additional optical fiber. Insome embodiments, the connector 104A can be keyed to so to ensure thatthe optical fibers in the connector 501 have the proper orientation. Theconnector 104A is configured to ensure that single-polarization opticalcouplers 207 on the chip 103A are matched to polarization-controlledconnections, such as L1-L4, and to ensure that polarization-diverseoptical couplers 211 on the chip 103A are matched to low-PWDconnections, such as the receive optical data connections R1-R4. In theexample connector 104A, the optical fiber cores are arranged in a singleline. However, in various embodiments, the optical fiber cores can bearranged in other ways, such as in a multiple line arrangement or in atriangular lattice arrangement, among other arrangements. In someembodiments, a spacing between adjacent optical fiber cores within theconnector 104A is either about 250 micrometers or about 125 micrometersto correspond with standard non-PMF optical fiber ribbon configurationsand connectors. However, it should be understood that in variousembodiments the spacing between adjacent optical fiber cores within theconnector 104A can be set at essentially any size that provides forconnection with the connector 501 or with other fiber ribbonconfigurations and connectors. In some embodiments, spacing betweenadjacent optical fiber cores within the connector 104A is reduced tocorrespond with a reduced spacing of the on-chip optical couplingelements, which corresponds to a reduced chip footprint of the opticalcoupling array, which may have benefits in cost and thermal managementof the chip. Reduction in the spacing between adjacent optical fibercores within the connector 104A can include use of a tapered fiberbundle and/or a multicore fiber.

In some embodiments, the connector 104A can be configured as aconnectorized optical focusing assembly that forms part of the opticalconnection between the chip 103A and the laser light supply system 101,and/or between the chip 103A and the link-fiber interface. For example,the GRIN focusing elements within the connector 104A can be configuredto direct light propagating in each optical fiber mode into a focusedspot. The array of GRIN focusing elements within the connector 104A cangenerate an arrangement of such focused spots to match with an array ofoptical coupling elements on the chip 103A. It should be appreciatedthat connector 104A provides for easy connection, disconnection, andre-connection for testing, building, etc., and may include a standardribbon connector. The connector 104A configured as a connectorizedoptical focusing assembly can be fabricated by splicing SMF,graded-index optical fiber, and possibly coreless optical fiber, alongwith an angled cleave or prism that re-directs light towards the chip103A, such as discussed with regard to FIGS. 4A through 4E.

In some embodiments, optical fibers within the connector 104A may bepositioned in an array of grooves or channels, such as the “V” groovesdiscussed with regard to FIG. 5A. The grooves or channels enable partialor complete alignment of the optical fibers in a passive manner. Forexample, optical fibers can be placed in the array of grooves orchannels passively (i.e., without actively monitoring light signalsthrough the optical fibers as they are placed in the array of grooves orchannels) so that the position of the optical fibers transverse to thegrooves/channels and the length direction of the optical fibers isfixed, with a final active alignment step used to adjust a single axialalignment of the optical fibers, i.e., to adjust the polarizationorientation of the optical fibers. And, in some embodiments, anadditional mechanical feature may be provided on the optical fibersand/or the connector 104A to properly orient the optical fibers at thecorrect axial alignment, thereby allowing passive axial alignment of theoptical fibers within the connector 104A. In various embodiments, thearray of grooves or channels can be formed in a substrate of theconnector 104A and/or in the chip 103A-103B.

In some embodiments, the connector 104A can be configured to interfacewith optical fiber ribbon or optical fiber arrays. In some embodiments,such interfacing optical fiber ribbons or arrays can be produced usingsmall-glass-outer-diameter optical fiber (e.g., optical fiber with80-micrometers or less glass-outer-diameter can be produced) with fibercoatings thinner than standard coatings. In some embodiments, theconnector 104A can be configured to interface with optical fiber ribbonor optical fiber arrays that have a core spacing of about 140micrometers or less. To achieve even smaller core spacing, one or moremulticore optical fibers can be used and the connector 104 can becorrespondingly configured to match the multicore arrangement. Forexample, a polarization-maintaining multicore fiber may be used toconnect the laser light supply system 101 to any of the chips 103A-103D.In some embodiments, a tapered multicore connector or tapered fiberbundle may be used as a fan-out from a dense arrangement of cores withinthe connector 104A to a more standard arrangement of cores withinoptical fibers, ribbons, and/or connectors that need to interface withthe connector 104A.

FIG. 7 shows a diagram of how the SQUID assembly 500 can be connected tothe laser light supply system 101, in accordance with some embodiments.In some embodiments, the connector 503 of the SQUID assembly 500 isconfigured to match the output interface 102 of the laser light supplysystem 101 to facilitate connecting to the laser light supply system 101during assembly of the optical module 101, as well as to facilitatetesting, repair, burn-in, etc. The connector 503 can be configured toinclude an array of short segments of optical fiber that are cleaved sothat the pattern of the cleaved ends of the segments of optical fibermatch the pattern of optical coupling sites in the output interface 102of the laser light supply system 101. In some embodiments, the connector503 can include an array of grooves or channels, such as “V” grooves, tofacilitate arrangement of the optical fibers within the connector 503 toenable matching of the optical fibers with the pattern of opticalcoupling sites in the output interface 102 of the laser light supplysystem 101.

In some embodiments, ends of the optical fibers that extend from theconnector 503 for interfacing with the output interface 102 of the laserlight supply system 101 can be formed by cleaving or otherwise cuttingthe optical fibers after the optical fibers have been fixed in positionrelative to each other in the grooves or channel or ribbon within theconnector 503, so that the relative axial cleave positions of theoptical fibers can be passively and precisely controlled and maintained.In some embodiments, the output interface 102 of the laser light supplysystem 101 may not have vertical optical couplers. In such embodiments,the connector 503 can be configured to match an array of edge-couplingsites within the output interface 102 of the laser light supply system101.

In some embodiments, the end of the optical fiber that extends from theconnector 503 for interfacing with the output interface 102 of the laserlight supply system 101 will have an end surface that is substantiallynormal to the axis of the optical fiber. In some embodiments, the endsurface of the optical fiber that extends from the connector 503 can beslightly, e.g., less than 15 degrees, off-normal relative to the axis ofthe optical fiber in order to reduce back-reflections. In someembodiments, the end surface of the optical fiber that extends from theconnector 503 can end in a prism or a larger-angle cleave to provide forturning of the laser beam, such as when an interposer is used tosubsequently redirect the laser beam.

In some embodiments, the connector 503 is configured to connect directlywith a semiconductor chip that includes the gain medium of the laserlight supply system 101. Or, in some embodiments, there may beintermediate components located between the connector 503 and the gainmedium of the laser light supply system 101. For example, an interposer,a semiconductor amplifier, a fiber amplifier, and/or an external cavitycan be positioned between the connector 503 and the gain medium of thelaser light supply system 101. Also, in various embodiments, theconnector 503 is configured in a way that provides for easy connectionwith one or more PMF ribbons or polarization-maintaining microcableswhich will connect the laser light supply system 101 to the chips103A-103D. In some embodiments, these PMF ribbons orpolarization-maintaining microcables may be part of the SQUID assembly500.

In some embodiments, the connector 503 is configured so that multiplePMF ribbons and/or polarization-maintaining microcables can plug intoimmediately adjacent positions along a standard connector within theoutput interface 102 of the laser light supply system 101. However, insome embodiments, the connector 503 is configured so that multiple PMFribbons and/or polarization-maintaining microcables may not plug intoimmediately adjacent positions along a standard connector within theoutput interface 102 of the laser light supply system 101. In theseembodiments, a breakout assembly can be provided to optically connectthe connector 503 to the output interface 102 of the laser light supplysystem 101. FIG. 8 shows the diagram of FIG. 7, with four breakoutassemblies 801A, 801B, 801C, 801D provided to connect the fourconnectors 503 to the output interface 102 of the laser light supplysystem 101, in accordance with some embodiments. Each of the breakoutassemblies 801A-801D is configured as an optical extension that includesa number of optical fibers and/or optical waveguides that match innumber and polarization alignment with optical fibers within theconnector 503 and with optical coupling sites within the outputinterface 102 of the laser light supply system 101. The breakoutassemblies 801A-801D provide for fan-out of the optical coupling siteswithin the output interface 102 of the laser light supply system 101 toenable easier connection of the connectors 503 to the output interface102, and to enable connection/removal of one connector 503 to/from theoutput interface 102 without disturbing connection of another connector503 with the output interface 102.

As discussed above, in some embodiments, the SQUID assembly 500 caninclude a PMF ribbon 507 or polarization-maintaining multicore opticalfiber for optically connecting the laser light supply system 101 to thechip 103A-103D. FIG. 9A shows an example vertical cross-section throughone type of PMF ribbon 901, in accordance with some embodiments. The PMFribbon 901 includes multiple optical cores 905 arranged in asubstantially linear alignment with each other. The PMF ribbon 901 alsoincludes stress-inducing members 903 that are substantially linearaligned with the multiple optical cores 905, such that each optical core905 is bracketed by a pair of stress-inducing members 903 in asubstantially similar spatial configuration. The stress-inducing members903 function to introduce birefringence within the multiple opticalcores 905, such that each of the optical cores 905 has a substantiallysame polarization alignment. The body of the PMF ribbon 901 isconfigured to maintain the linear arrangement of the multiple opticalcores 905 and stress-inducing members 903 along the length of the PMFribbon 901.

Also, the PMF ribbon 901 can include a flat outer surface 906 tofacilitate alignment of the PMF ribbon 901 with a matching opticalconnector. In some embodiments, with the multiple cores 905 arranged ina line, the birefringence axis of all cores 905, and the alignmentfeature (flat outer surface 906), and the displacement between cores 905all have the same direction. The perpendicular distance between the flatouter surface 906 and the center of the optical cores 905 can becontrolled to be small enough to allow improved optical couplingefficiency and to be large enough that light losses due to unwantedinteraction with the chip surface are negligible. In some embodiments,the perpendicular distance between the flat outer surface 906 and thecenter of the optical cores 905 can be controlled at less than about 62micrometers to enable efficient optical coupling even if an angledturning element in the optical coupling configuration has nograded-index or focusing portion. The flat outer surface 906 can enableorientation of the birefringent axes without the need to adjust theorientation of the birefringent axes using optical feedback. In someembodiments, the outer cladding/jacket of the PMF ribbon 901 can have ahigh aspect ratio that enables easy orientation and alignment of the PMFribbon 901 with a connector or interface structure. It should beunderstood that the birefringent axis of each core 905 of PMF ribbon 901is determined by the birefringence-inducing perturbations, such asstress-inducing members 903 (e.g., stress rods or the like), so thatcontrolling the orientation of the PMF ribbon 901 alone providessufficiently polarization-maintaining connectivity.

FIG. 9B shows an example vertical cross-section through another type ofPMF ribbon 907, in accordance with some embodiments. The PMF ribbon 907includes multiple optical cores 909, where each core 909 has anelliptical cross-sectional shape that creates inherent birefringencewithin the core 909. In some embodiments, the multiple optical cores 909are arranged in a substantially linear alignment with each other. Thebody of the PMF ribbon 907 is configured to maintain the lineararrangement of the multiple optical cores 909 along the length of thePMF ribbon 907. Also, the PMF ribbon 907 can include a flat outersurface 910 to facilitate alignment of the PMF ribbon 907 with amatching optical connector. In some embodiments, the spatialrelationship of the flat outer surface 910 is correlated to thebirefringence orientation of the multiple cores 909, so that positioningof the flat outer surface 910 will reliably control the birefringenceorientation of the multiple cores 909. The perpendicular distancebetween the flat outer surface 910 and the center of the optical cores909 can be controlled to be small enough to allow improved opticalcoupling efficiency and to be large enough that light losses due tounwanted interaction with the chip surface are negligible. In someembodiments, the perpendicular distance between the flat outer surface910 and the center of the optical cores 909 can be controlled at lessthan about 62 micrometers to enable efficient optical coupling even ifan angled turning element in the optical coupling configuration has nograded-index or focusing portion. The flat outer surface 910 can enableorientation of the birefringent axes without the need to adjust theorientation of the birefringent axes using optical feedback. In someembodiments, the outer cladding/jacket of the PMF ribbon 907 can have ahigh aspect ratio that enables easy orientation and alignment of the PMFribbon 907 with a connector or interface structure. It should beunderstood that the birefringent axis of each core 909 of PMF ribbon 907is determined by the birefringence-inducing elliptical shape of thecores 909, so that controlling the orientation of the PMF ribbon 907alone provides sufficiently polarization-maintaining connectivity.

FIG. 9C shows an example vertical cross-section through apolarization-maintaining multicore optical fiber (PMMF) 911, inaccordance with some embodiments. In the PMMF 911, three optical cores915 are symmetrically positioned around a central stress-inducing member913, such as a stress rod or the like. The stress-inducing member 913functions to introduce birefringence within the multiple optical cores915, such that the birefringent axes of the optical cores 915 areradially directed about the stress-inducing member 913. The body of thePMMF 911 is configured to maintain the arrangement of the multipleoptical cores 915 and stress-inducing member 913 along the length of thePMMF 911. Also, the PMMF 911 can include a flat outer surface 917 tofacilitate alignment of the PMMF 911 with a matching optical connector.In some embodiments, the spatial relationship of the flat outer surface917 is correlated to the birefringence orientations of the multiplecores 915, so that positioning of the flat outer surface 917 willreliably control the birefringence orientations of the multiple cores915. The flat outer surface 917 can enable orientation of thebirefringent axes of the multiple cores 915 without the need to adjustthe orientation of the birefringent axes using optical feedback.

FIG. 9D shows an example vertical cross-section through another type ofPMF ribbon 918, in accordance with some embodiments. FIG. 9D also showsa preform 918A of the PMF ribbon 918, before the preform 918A is drawnto create the PMF ribbon 918. The preform 918A includes a number ofPMF's 919 positioned in a substantially linearly aligned configuration.The preform 918A also includes a number of alignment components 927positioned at top and bottom interfaced between adjacently positionedPMF's 919. Each PMF 919 includes an optical core 925 and stress-inducingmembers 921 to created birefringence in the optical core 925. The PMF's919 are axially aligned so that the birefringent axis of each PMF 919 isaligned in the same direction. The PMF's 919 shown in the example ofFIG. 9D are PANDA-type PMF's 919. However, it should be understood thatin other embodiments, the PMF's 919 can be other types of PMF's, such asbow-tie-type PMF's 919, among others. As the preform 918A is drawn toproduce the PMF ribbon 918, the alignment components 927 flow tosubstantially fill interstitial spacings between the PMF's 919 and thensolidify to form an outer cladding 929 that physically secures the PMF's919 in their linear arrangement with respect to each other. Also,drawing of the preform 918A to create the PMF ribbon 918 can be done toform one or more alignment features on the exterior surface of the PMFribbon 918. In the example of FIG. 9D, the preform 918A is drawn tocreate the PMF ribbon 918 having an alignment feature that is a flatsurface 931 on the outside of the PMF ribbon 918. It should beappreciated that the flat surface 931 on the outside of the PMF ribbon918 can be formed without polishing. Also, it should be understood thatin other embodiments, the alignment feature(s) on the exterior surfaceof the PMF ribbon 918 can have various cross-sectional shapes, such asgrooves or channels.

The flat outer surface 931 can facilitate alignment of the PMF ribbon918 with a matching optical connector. In some embodiments, the spatialrelationship of the flat outer surface 931 is correlated to thebirefringence orientation of the multiple cores 925, so that positioningof the flat outer surface 931 will reliably control the birefringenceorientation of the multiple cores 925. The perpendicular distancebetween the flat outer surface 931 and the center of the optical cores925 can be controlled to be small enough to allow improved opticalcoupling efficiency and to be large enough that light losses due tounwanted interaction with the chip surface are negligible. In someembodiments, the perpendicular distance between the flat outer surface931 and the center of the optical cores 925 can be controlled at lessthan about 62 micrometers to enable efficient optical coupling even ifan angled turning element in the optical coupling configuration has nograded-index or focusing portion. The flat outer surface 931 can enableorientation of the birefringent axes without the need to adjust theorientation of the birefringent axes using optical feedback. In someembodiments, the outer cladding 929 of the PMF ribbon 918 can have ahigh aspect ratio that enables easy orientation and alignment of the PMFribbon 918 with a connector or interface structure.

In some embodiments, the preform 918A for the PMF ribbon 918 may beconfigured without use of pre-manufactured PMF's 919. More specifically,the preform 918A can be configured to include cladding materials(similar to the alignment components 927), optical core elements, andbirefringence-inducing members, as well as possible voids used to obtaincontrolled deformations. The stress induced by thebirefringence-inducing members can be controlled by selecting materialswith large differences in thermal expansion (e.g., Boron-doped silica).The preform 918A may be produced through a combination of machining(e.g., drilling holes), stacking, overcladding, and other processes.

FIG. 10 shows an example of a quasi-polarization maintaining opticalfiber assembly (QPMFA) 1001, in accordance with some embodiments. TheQPMFA 1001 is formed by wrapping a number of SMF's 1005A, 1005B, 1005C,1005D around a form (or filament) 1003 so that controlled birefringenceis introduced into the multiple SMF's 1005A-1005D. It should beunderstood that the inclusion of four SMF's 1005A-1005D in the QPMFA1001 is shown by way of example. In various embodiments, the QPMFA 1001can include either less than four SMF's or more than four SMF's. Themultiple SMF's 1005A-1005D are around the form 1003 in a controlledmanner to create a helix of the multiple SMF's 1005A-1005D. Thecurvature of the helix of the multiple SMF's 1005A-1005D is correlatedto the birefringence that is introduced into the multiple SMF's1005A-1005D. The curvature (κ) of the helix of the multiple SMF's1005A-1005D is given by Equation 1, where (R) is the radius of the helixand (Λ) is the period of the helix.

$\begin{matrix}{\kappa = {\frac{R}{\left( {R^{2} + \left( \frac{\Lambda}{2\;\pi} \right)^{2}} \right)}.}} & {{Equation}\mspace{14mu} 1}\end{matrix}$

In some embodiments, the helix of the multiple SMF's 1005A-1005D isformed by wrapping a ribbon of the SMF's 1005A-1005D (ornon-polarization-maintaining fibers) around form 1003 so that the ribbonof the SMF's 1005A-1005D has a substantial bend-induced birefringencealong a known bend axis relative to the ribbon of the SMF's 1005A-1005D.As shown in Equation 1, the local curvature (κ) is related to the helixperiod (Λ) and the helix radius (R), which can be controlled byappropriately selecting a form 1003 and wrapping parameters for theSMF's 1005A-1005D around the form 1003. In various embodiments, theSMF's 1005A-1005D can be bound to the form 1003 using an adhesive and/orby enclosing them in a jacket material. In some embodiments, amulti-core optical fiber with elongated cladding can be used instead ofthe ribbon of SMF's 1005A-1005D.

In some embodiments, an SMF ribbon can be produced and attached to acurled cable support element that is flexible enough to use for routing,but that tends to assume a helical shape. In these embodiments, the SMFfiber ribbon can be bonded to the curled cable support element byadhesion, or enclosed within it, or both the SMF fiber ribbon and thecurled cable support element can be enclosed in a jacket material.

An amount of achievable birefringence is limited by fiber breakage. Insome embodiments, the bend diameter of the SMF fibers about the form1003 is greater than or equal to about 4 millimeters. FIG. 11 shows aplot of birefringence (beat length) as a function of radius of curvatureof SMF fiber, in accordance with some embodiments. FIG. 11 shows thatbirefringence of around dnB=1.3e-4 (beat length of about 1 centimeter)can be achieved for SMF fiber bend diameters greater than or equal toabout 4 millimeters (radius of curvature of SMF fiber greater than orequal to about 2 millimeters). Therefore, a regime ofquasi-polarization-maintaining operation is achievable in SMF fiber bycontrolled bending of the SMF fiber. In some embodiments, the QPMFA 1001is configured to ensure that the local SMF fiber 1005A-1005B benddiameter remains greater than or equal to about 4 millimeters at eachlocation along the length of the form 1003. In an example embodiment,the QPMFA 1001 is configured to have a radius (R) of the helix equal toabout 2 millimeters, and a period (Λ) of the helix equal to about 2millimeters. In this example embodiment, about 6 centimeters of theSMF's 1005A-1005B is needed to transport light about 1 centimeter alongthe form 1003. In another example embodiment, the QPMFA 1001 isconfigured to have a radius (R) of the helix equal to about 1.5millimeters, and a period (Λ) of the helix equal to about 6 millimeters.In this example embodiment, about 1.9 centimeters of the SMF's1005A-1005B is needed to transport light about 1 centimeter along theform 1003. It should be understood that the above-mentioned values forthe radius (R) of the helix and the period (Λ) of the helix are providedby way of example. In various embodiments, the radius (R) of the helixand the period (Λ) of the helix can be defined as needed to create theQPMFA 1001.

In some embodiments, an optical module (e.g., 100) is disclosed. Theoptical module (e.g., 100) can include a housing or exterior structure.In some embodiments, the optical module (e.g., 100) can also include alaser light supply system (e.g., 101) disposed within the housing. Inother embodiments, the laser light supply system (e.g., 101) can bedisposed outside of the housing of the optical module (e.g., 100). Thelaser light supply system (e.g., 101) has a laser output optical port. Achip (e.g., 103A-103D) is disposed within the housing of the opticalmodule (e.g., 100). The chip (e.g., 103A-103D) includes a laser inputoptical port (e.g., 207), and a transmit data optical port (e.g., 209),and a receive data optical port (e.g., 211). The optical module (e.g.,100) also includes a link-fiber interface exposed at an exterior surfaceof the housing. The link-fiber interface includes a transmit dataconnector (e.g., T) and a receive data connector (e.g., R). The opticalmodule (e.g., 100) also includes a polarization-maintaining opticalfiber (e.g., 201) optically connected between the laser output opticalport and the laser input optical port (e.g., 107) of the chip (e.g.,103A-103D). The optical module (e.g., 100) also includes a firstnon-polarization-maintaining optical fiber (e.g., 203) opticallyconnected between the transmit data optical port (e.g., 209) of the chip(e.g., 103A-103D) and the transmit data connector (T) of the link-fiberinterface. The optical module (e.g., 100) also includes a secondnon-polarization-maintaining optical fiber (e.g., 205) opticallyconnected between the receive data optical port (e.g., 211) of the chip(e.g., 103A-103D) and the receive data connector (R) of the link-fiberinterface.

In some embodiments, a chip connector (e.g., 104A-104D) is configured todirect light output from the polarization-maintaining optical fiber(e.g., 201) into the laser input optical port (e.g., 207) of the chip(e.g., 103A-103D). The chip connector (e.g., 104A-104D) is configured todirect light output from the transmit data optical port (e.g., 209) ofthe chip (e.g., 103A-103D) into the first non-polarization-maintainingoptical fiber (e.g., 203). The chip connector (e.g., 104A-104D) is alsoconfigured to direct light output from the secondnon-polarization-maintaining optical fiber (e.g., 205) into the receivedata optical port (e.g., 211) of the chip (e.g., 103A-103D). In someembodiments, the chip connector (e.g., 104A-104D) is configured to turnthe laser light between the output from the polarization-maintainingoptical fiber (e.g., 201) and the laser input optical port (e.g., 207)of the chip (e.g., 103A-103D). Also, in some embodiments, the chipconnector (e.g., 104A-104D) is configured to turn the light output fromthe transmit data optical port (e.g., 209) of the chip (e.g., 103A-103D)between the transmit data optical port (e.g., 209) of the chip (e.g.,103A-103D) and the first non-polarization-maintaining optical fiber(e.g., 203). In some embodiments, the chip connector (e.g., 104A-104D)is configured to turn the light output from the secondnon-polarization-maintaining optical fiber (e.g., 205) between thesecond non-polarization-maintaining optical fiber (e.g., 205) and thereceive data optical port (e.g., 211) of the chip (e.g., 103A-103D). Insome embodiments, a laser connector (e.g., 102) is configured to directlaser light output from the laser light supply system (e.g., 101) to thepolarization-maintaining optical fiber (e.g., 201). In some embodiments,the laser connector (e.g., 102) is configured to turn the laser lightbetween the laser output optical port of the laser light supply system(e.g., 101) and the polarization-maintaining optical fiber (e.g., 201).

In some embodiments, the laser light supply system (e.g., 101) hasmultiple laser output optical ports, and the chip (e.g., 103A-103D) hasmultiple laser input optical ports (e.g., 207), and the chip (e.g.,103A-103D) has a separate transmit data optical port (e.g., 209) foreach of the multiple laser input optical ports of the laser light supplysystem (e.g., 101), and the chip (e.g., 103A-103D) has a separatereceive data optical port (e.g., 211) for each of the multiple laserinput optical ports of the laser light supply system (e.g., 101). Inthis manner, the chip (e.g., 103A-103D) has a separate fiber set 200 foreach of the multiple laser input optical ports of the laser light supplysystem (e.g., 101). Also, in some embodiments, the link-fiber interfaceincludes a separate transmit data connector (e.g., T) for each transmitdata optical port (e.g., 209) of the chip (e.g., 103A-103D). Also, thelink-fiber interface includes a separate receive data connector (e.g.,R) for each receive data optical port (e.g., 211) of the chip (e.g.,103A-103D). Additionally, each laser output optical port is opticallyconnected to a corresponding one of the multiple laser input opticalports (e.g., 207) of chip (e.g., 103A-103D) through a separatepolarization-maintaining optical fiber (e.g., 201). And, each transmitdata optical port (e.g., 209) is connected to a corresponding transmitdata connector (e.g., T) of the link-fiber interface through a separatenon-polarization-maintaining optical fiber (e.g., 203). And, eachreceive data optical port (e.g., 211) is connected to a correspondingreceive data connector (e.g., R) of the link-fiber interface through aseparate non-polarization-maintaining optical fiber (e.g., 205).

In some embodiments, the multiple laser output optical ports includefour laser output optical ports. And, the multiple laser input opticalports (e.g., 207) of a given chip (e.g., 103A-103D) include four laserinput optical ports (e.g., 207), such as shown in FIG. 3. And, the chip(e.g., 103A-103D) includes four transmit data optical ports (e.g., 209),such as shown in FIG. 3. And, the chip (e.g., 103A-103D) includes fourreceive data optical ports (e.g., 211), such as shown in FIG. 3. And,the link-fiber interface includes four transmit data connectors (e.g.,T) four receive data connectors (e.g., R) for each chip (e.g.,103A-103D).

In some embodiments, the chip (e.g., 103A-103D) is one of multiple chipswithin the optical module (e.g., 100). And, each of the multiple chips(e.g., 103A-103D) includes multiple laser input optical ports (e.g.,207). And, each of the multiple chips (e.g., 103A-103D) includesmultiple transmit data optical ports (e.g., 209), such that a given chiphas a separate transmit data optical port (e.g., 209) for each of themultiple laser input optical ports (e.g., 207) of the given chip (e.g.,103A-103D). Also, each of the multiple chips (e.g., 103A-103D) includesmultiple receive data optical ports (e.g., 211), such that a given chip(e.g., 103A-103D) has a separate receive data optical port (e.g., 211)for each of the multiple laser input optical ports (e.g., 207) of thegiven chip (e.g., 103A-103D). Also, the laser light supply system (e.g.,101) can include a separate laser output optical port for each of thelaser input optical ports (e.g., 207) of the multiple chips (e.g.,103A-103D) within the optical module (e.g., 100). Also, the link-fiberinterface of the optical module (e.g., 100) can include a separatetransmit data connector (e.g., T) for each transmit data optical port(e.g., 209) of the multiple chips (e.g., 103A-103D). And, the link-fiberinterface can include a separate receive data connector (e.g., R) foreach receive data optical port (e.g., 211) of the multiple chips (e.g.,103A-103D). Also, each laser output optical port is optically connectedto a corresponding one of the laser input optical ports (e.g., 207) ofthe multiple chips (e.g., 103A-103D) through a separatepolarization-maintaining optical fiber (e.g., 201). And, each transmitdata optical port (e.g., 209) of the multiple chips (e.g., 103A-103D) isconnected to a corresponding transmit data connector (e.g., T) of thelink-fiber interface through a separate non-polarization-maintainingoptical fiber (e.g., 203). And, each receive data optical port (e.g.,211) of the multiple chips (e.g., 103A-103D) is connected to acorresponding receive data connector (e.g., R) of the link-fiberinterface through a separate non-polarization-maintaining optical fiber(e.g., 205).

In some embodiments, the optical module (e.g., 100) includes a separateset of polarization-maintaining optical fibers (e.g., L1-L4, or L5-L8,or L9-L12, or L13-L16) for each of the multiple chips (e.g., 103A-103D),where a given set of polarization-maintaining optical fibers (e.g.,L1-L4, or L5-L8, or L9-L12, or L13-L16) is disposed to optically connectthe multiple laser input optical ports (e.g., 207) of a given chip(e.g., 103A-103D) to corresponding multiple laser output optical portsof the laser light supply system (e.g., 101). In some embodiments, thegiven set of polarization-maintaining optical fibers (e.g., L1-L4, orL5-L8, or L9-L12, or L13-L16) is configured in apolarization-maintaining optical fiber ribbon. Thepolarization-maintaining optical fiber ribbon is configured to maintaina same polarization alignment for each polarization-maintaining opticalfiber (e.g., 201) within the given set of polarization-maintainingoptical fibers (e.g., L1-L4, or L5-L8, or L9-L12, or L13-L16). In someembodiments, the same polarization alignment is spatially correlated toan alignment surface on an exterior of the polarization-maintainingoptical fiber ribbon. In some embodiments, a chip connector (e.g., 501)is configured to direct light output from each polarization-maintainingoptical fiber (e.g., 201) into a corresponding laser input optical port(e.g., 207) of a given chip of the multiple chips (e.g., 103A-103D),where the chip connector (e.g., 501) is optically connected to an end ofthe polarization-maintaining optical fiber ribbon. In some embodiments,a laser connector (e.g., 503) is configured to direct laser light outputfrom separate laser output optical ports of the laser light supplysystem (e.g., 101) into corresponding separate polarization-maintainingoptical fibers (e.g., 201) within the polarization-maintaining opticalfiber ribbon, where the laser connector (e.g., 503) is opticallyconnected to a first end of the polarization-maintaining optical fiberribbon, and where the chip connector (e.g., 501) is optically connectedto a second end of the polarization-maintaining optical fiber ribbon. Insome embodiments, the laser connector (e.g., 503) is optically connectedto multiple separate polarization-maintaining optical fiber ribbons.

In some embodiments, the chip connector (e.g., 104A-104D) is configuredto direct light output from each the transmit data optical ports (e.g.,209) of the given chip (e.g., 103A-103D) into a correspondingnon-polarization-maintaining optical fiber (e.g., 203) that is opticallyconnected to a corresponding transmit data connector (e.g., T) of thelink-fiber interface. And, the chip connector (e.g., 104A-104D) isconfigured to direct light into the receive data optical port (e.g.,211) of the given chip (e.g., 103A-103D) from a correspondingnon-polarization-maintaining optical fiber (e.g., 205) that is opticallyconnected to a corresponding receive data connector (e.g., R) of thelink-fiber interface. In some embodiments, the correspondingnon-polarization-maintaining optical fiber (e.g., 203) that is opticallyconnected to the corresponding transmit data connector (e.g., T) of thelink-fiber interface and the corresponding non-polarization-maintainingoptical fiber (e.g., 205) that is optically connected to thecorresponding receive data connector (e.g., R) of the link-fiberinterface are co-located within a multiple non-polarization-maintainingoptical fiber structure. In some embodiments, each of the multiple chips(e.g., 103A-103D) includes four laser input optical ports (e.g., 207),such as shown in FIG. 3. And, the given set of polarization-maintainingoptical fibers (e.g., 201) includes four polarization-maintainingoptical fibers (e.g., L1-L4, or L5-L8, or L9-L12, or L13-L16). Also, insome embodiments, the multiple chips within the optical module (e.g.,100) includes four chips (e.g., 103A-103D).

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin other embodiments, even if not specifically shown or described. Suchvariations of the example embodiments disclosed herein are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

Although the foregoing invention has been described in some detail forpurposes of clarity of understanding, it will be apparent that certainchanges and modifications can be practiced within the scope of theinvention description. Accordingly, the example embodiments disclosedherein are to be considered as illustrative and not restrictive, and theinvention is not to be limited to the details given herein, but may bemodified within the scope and equivalents of the described embodiments.

What is claimed is:
 1. An optical module, comprising: a housing; a laser light supply system disposed within the housing, the laser light supply system having a laser output optical port; a chip disposed within the housing, the chip having a laser input optical port and a transmit data optical port and a receive data optical port; a link-fiber interface exposed at an exterior surface of the housing, the link-fiber interface including a transmit data connector and a receive data connector; a polarization-maintaining optical fiber optically connected between the laser output optical port and the laser input optical port of the chip; a first non-polarization-maintaining optical fiber optically connected between the transmit data optical port of the chip and the transmit data connector of the link-fiber interface; and a second non-polarization-maintaining optical fiber optically connected between the receive data optical port of the chip and the receive data connector of the link-fiber interface; a chip connector attached to the chip, the chip connector having one or more angled light turning elements, at least one of the one or more angled turning elements configured and positioned to re-direct light from the polarization-maintaining optical fiber into the laser input optical port of the chip, at least one of the one or more angled turning elements configured and positioned to re-direct light from the transmit data optical port of the chip into the first non-polarization-maintaining optical fiber, at least one of the one or more angled turning elements configured and positioned to re-direct light from the second non-polarization-maintaining optical fiber into the receive data optical port of the chip.
 2. The optical module as recited in claim 1, further comprising: a laser connector configured to direct laser light output from the laser light supply system to the polarization-maintaining optical fiber.
 3. The optical module as recited in claim 2, wherein the laser connector is configured to turn the laser light between the laser output optical port and the polarization-maintaining optical fiber.
 4. The optical module as recited in claim 1, wherein the laser light supply system has multiple laser output optical ports, wherein the chip has multiple laser input optical ports, wherein the chip has a separate transmit data optical port for each of the multiple laser input optical ports, wherein the chip has a separate receive data optical port for each of the multiple laser input optical ports, wherein the link-fiber interface includes a separate transmit data connector for each transmit data optical port of the chip, wherein the link-fiber interface includes a separate receive data connector for each receive data optical port of the chip, wherein each laser output optical port is optically connected to a corresponding one of the multiple laser input optical ports of chip through a separate polarization-maintaining optical fiber, wherein each transmit data optical port is connected to a corresponding transmit data connector of the link-fiber interface through a separate non-polarization-maintaining optical fiber, and wherein each receive data optical port is connected to a corresponding receive data connector of the link-fiber interface through a separate non-polarization-maintaining optical fiber.
 5. The optical module as recited in claim 4, wherein the multiple laser output optical ports include four laser output optical ports, and wherein the multiple laser input optical ports include four laser input optical ports, and wherein the chip includes four transmit data optical ports, and wherein the chip includes four receive data optical ports, and wherein the link-fiber interface includes four transmit data connectors, and wherein the link-fiber interface includes four receive data connectors.
 6. An optical module, comprising: a housing; a laser light supply system disposed within the housing, the laser light supply system having a laser output optical port; a chip disposed within the housing, the chip having a laser input optical port and a transmit data optical port and a receive data optical port; a link-fiber interface exposed at an exterior surface of the housing, the link-fiber interface including a transmit data connector and a receive data connector; a polarization-maintaining optical fiber optically connected between the laser output optical port and the laser input optical port of the chip; a first non-polarization-maintaining optical fiber optically connected between the transmit data optical port of the chip and the transmit data connector of the link-fiber interface; and a second non-polarization-maintaining optical fiber optically connected between the receive data optical port of the chip and the receive data connector of the link-fiber interface, wherein the chip is one of multiple chips within the optical module, each of the multiple chips including multiple laser input optical ports, each of the multiple chips including multiple transmit data optical ports such that a given chip has a separate transmit data optical port for each of the multiple laser input optical ports of the given chip, each of the multiple chips including multiple receive data optical ports such that a given chip has a separate receive data optical port for each of the multiple laser input optical ports of the given chip, wherein the laser light supply system includes a separate laser output optical port for each of the laser input optical ports of the multiple chips, wherein the link-fiber interface includes a separate transmit data connector for each transmit data optical port of the multiple chips, wherein the link-fiber interface includes a separate receive data connector for each receive data optical port of the multiple chips, wherein each laser output optical port is optically connected to a corresponding one of the laser input optical ports of the multiple chips through a separate polarization-maintaining optical fiber, wherein each transmit data optical port of the multiple chips is connected to a corresponding transmit data connector of the link-fiber interface through a separate non-polarization-maintaining optical fiber, and wherein each receive data optical port of the multiple chips is connected to a corresponding receive data connector of the link-fiber interface through a separate non-polarization-maintaining optical fiber.
 7. The optical module as recited in claim 6, wherein the optical module includes a separate set of polarization-maintaining optical fibers for each of the multiple chips, wherein a given set of polarization-maintaining optical fibers is disposed to optically connect the multiple laser input optical ports of a given chip to corresponding multiple laser output optical ports of the laser light supply system.
 8. The optical module as recited in claim 7, wherein the given set of polarization-maintaining optical fibers is configured in a polarization-maintaining optical fiber ribbon.
 9. The optical module as recited in claim 8, wherein the polarization-maintaining optical fiber ribbon is configured to maintain a same polarization alignment for each polarization-maintaining optical fiber within the given set of polarization-maintaining optical fibers.
 10. The optical module as recited in claim 9, wherein the same polarization alignment is spatially correlated to an alignment surface on an exterior of the polarization-maintaining optical fiber ribbon.
 11. The optical module as recited in claim 10, further comprising: a chip connector configured to direct light output from each polarization-maintaining optical fiber into a corresponding laser input optical port of a given chip of the multiple chips, wherein the chip connector is optically connected to an end of the polarization-maintaining optical fiber ribbon.
 12. The optical module as recited in claim 11, further comprising: a laser connector configured to direct laser light output from separate laser output optical ports of the laser light supply system into corresponding separate polarization-maintaining optical fibers within the polarization-maintaining optical fiber ribbon, wherein the laser connector is optically connected to a first end of the polarization-maintaining optical fiber ribbon, and wherein the chip connector is optically connected to a second end of the polarization-maintaining optical fiber ribbon.
 13. The optical module as recited in claim 12, wherein the laser connector is optically connected to multiple separate polarization-maintaining optical fiber ribbons.
 14. The optical module as recited in claim 12, wherein the chip connector is configured to direct light output from each the transmit data optical ports of the given chip into a corresponding non-polarization-maintaining optical fiber that is optically connected to a corresponding transmit data connector of the link-fiber interface, and wherein the chip connector is configured to direct light into the receive data optical port of the given chip from a corresponding non-polarization-maintaining optical fiber that is optically connected to a corresponding receive data connector of the link-fiber interface.
 15. The optical module as recited in claim 14, wherein the corresponding non-polarization-maintaining optical fiber that is optically connected to the corresponding transmit data connector of the link-fiber interface and the corresponding non-polarization-maintaining optical fiber that is optically connected to the corresponding receive data connector of the link-fiber interface are co-located within a multiple non-polarization-maintaining optical fiber structure.
 16. The optical module as recited in claim 15, wherein each of the multiple chips includes four laser input optical ports, and wherein the given set of polarization-maintaining optical fibers includes four polarization-maintaining optical fibers.
 17. The optical module as recited in claim 16, wherein the multiple chips includes four chips.
 18. The optical module as recited in claim 1, wherein the chip connector includes a plurality of grooves configured to align optical fibers to the chip, the plurality of grooves including a first groove for aligning the polarization-maintaining optical fiber to the chip, the plurality of grooves including a second groove for aligning the first non-polarization-maintaining optical fiber to the chip, the plurality of grooves including a third groove for aligning the second non-polarization-maintaining optical fiber to the chip.
 19. The optical module as recited in claim 18, wherein the first groove is configured to provide for passive alignment of the polarization-maintaining optical fiber with the laser input optical port of the chip, wherein the second groove is configured to provide for passive alignment of the first non-polarization-maintaining optical fiber with the transmit data optical port of the chip, wherein the third groove is configured to provide passive alignment of the second non-polarization-maintaining optical fiber with the receive data optical port of the chip.
 20. The optical module as recited in claim 18, wherein the plurality of grooves are configured as V-shaped grooves.
 21. The optical module as recited in claim 18, wherein the plurality of grooves are oriented parallel with each other in a groove array.
 22. The optical module as recited in claim 1, wherein the chip connector includes one or more focusing elements, at least one of the one or more focusing elements configured to focus re-directed light from the polarization-maintaining optical fiber onto the laser input optical port of the chip, at least one of the one or more focusing elements configured to focus re-directed light from the transmit data optical port onto an optical core of the first non-polarization-maintaining optical fiber, at least one of the one or more focusing elements configured to focus re-directed light from the second non-polarization-maintaining optical fiber onto the receive data optical port of the chip.
 23. The optical module as recited in claim 1, wherein at least one of the angled light turning elements includes an angled reflecting surface.
 24. The optical module as recited in claim 1, wherein the angled reflecting surface includes one or more coatings. 